Heating device



K. W. KNAPP AND W. G. HOLMES.

HEATING DEVICE. APPLICATION FILED MAR. 23, 1921.

Patented Dec. 27, 1921;

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K. w. KNAPP'TAND w. G. HOLMEs. HEATING DEVICE.

APPLICATION FILED MAR.23, I9ZI.

Patented Dec. 27, 192- 1".

[Tu/en for: Karl WKnapp I Va/ier 6 [10111165 yO/WKM His/l #071167 KARL w. xNArr, or nns MGINES, IowA, AND WALTER G. nomarsor. MINNEAPOLIS, MINNESOTA, AssIsNons To M. r. rATTnnsoN DENTAL SUPPLY ooMr'ANY, or sT. PAUL, MINNESOTA, A coaroaATioN or iLLINoIs.

HEATING DEVICE.

Specification of Letters Patent. Pat t d D 27 1921 Application filed March 23, 1921. Serial No. 454,819.

T 0 all whom itmay concern:

Be it known that we, KARL W. KNAPP, a citizen of the United States, resident of 'Des Moines, county of Polk, State of Iowa,

and WALTER G. HOLMES, a citizen of the United States, resident of Minneapolis, county of Hennepin, State of Minnesota, have jointly invented new and useful Improvements in Heating Devices, of which the 1 following is a specification.

This invention relates to improvements in heating devices and more particularly relates to improvements in heating devices adapted to heat flasks containing invested patterns in the dental art. This device is adapted to employ a combustible gas as the heat-producing agent and is provided with a supporting means adapted to have positioned thereon the usual type of cylindrical flask in which a wax model or pattern of the shape of the desired casting is placed and surrounded by the investment material. This wax pattern is usually terminally mounted upon a sprue rod which extends through the investment material so that, upon withdrawal of the rod, a passage is provided for the introduction, after removal of the wax, of the molten metal out of which the casting is to be formed.

While useful generally in this casting art, this novel device is particularly adapted to carry out the process invented by Karl W. Knapp, one of the joint inventors hereof, which is set forth in pending application Serial Number 399,688. This device adapted suddenly to apply a high temperature to the peripheral exterior of a flask. This heat is gradually communicated through the moist investment material to the wax which becomes fluid at a temperature below 212 degrees F. The radiated heat progress sively drives inwardly molecules of free water adjacent the flask in such a manner material to the pattern cavity and will force ahead oflt the water that has not been con verted into steamQ This water,u nder pressure of the steam, will practically allflow into the mold cavity and will carry with it the melted wax through the passage formed by the wlthdrawal of the sprue rod. Obviously, as the heat further penetrates theinvestment-material, more and more moisture wlll be driven out and all traces of'the melted wax will be removed so that the wax will not be absorbed by theinvestment material thereby eliminating all wax so that there will notbe'any wax or wax residues left to be burned or carbonized in themold to form a lining therein disadvantageous to perfect dental'castings. I The object therefore of this invention is to provide animproved heating device."

' Other objects of the invention will more fully appear from the'following description and the accompanying drawings and will be pointed out in the annexed claims.

In the accompanying drawings, there has i Fig. 2 is a vertical sectional view of the 7 device and through afpositioned flask;

v Fig. 3 is a vertical sectional view on the line 3 3 of Fig. 2, but with the drip cup,

flask and associated parts omitted; V

' Fig. 4 is a cross-sectional view on the line 44l of Fig, 3; 1'

v Fig. 5 is an enlarged detail view of the gas valve on the line 5'-'5 of Fig. 3, and

Fig. 6 is an enlarged detail view of the.

gas outlet and valve on the line 6-6' of .Fig. 2. A

In this selected embodiment of the invention there isprovided a casing 7 to. support the several parts of the device. It is gen- 'erally of 'an' upwardly tapered cylindrical bottom. Within the casing is positioned the supporting means for the usual flask 8 .containing the wax pattern 9 surroundedby conformation and is open at the top and V longitudinally spaced relation.

shape and may be closed at one end, either permanently or demountably so. The other end of the metallic flask is preferably concentrically stepped as shown in Fig. 2.

The novel flask-supporting means here disclosed comprises a hollow ring 18 here shown as square in section. This ring not only provides a support for the usual. flask but also provides a passage for combustible gas adapted to be received therein from a suitable source of supply. The gas-jetting means are annularly disposed and, in the form disclosed, comprise a plurality of tubular members 14: upwardly projecting from the ring 13 and communicating with the interior thereof to receive the gas. Each tubular member let is provided with a plurality of apertures or ports 15 arranged in Preferably these ports 15 are disposed, as here disclosed, to discharge the combustible gas substantially tangentially and inwardly. This tangential porting of the gas creates, when the gas is ignited, substantially a vortex of hot flames.

The cylindrical flask. may be supported directly by the ring but it is preferred to provide a drip-receiving cup lGclosed at its lower end and having an annular flaring flange 17 at its upper open end. This flange is provided with a plurality of annularly disposed pins 18 by which the flange is supported in spaced relation to the ring 13. This mode of support permits circulation of air arising between the ring interior and the smaller-diametered exterior of the cup. The upper face of the cup-flange is provided with an annular fiat portion 19adapted to receive thereon the annularly disposed pins 21 or" the annulus 22 upon which the flask is adapted to be mounted. The upper surface oi this annulus is concentrically stepped to correspond with the similar construction of the flask end. The provision of the pins 21 annulus from the cup flange whereby circulation of air or escape of steam and moisture is facilitated. The function of the cup 16 is to collect the melted wax from the flask as well as water driven therefrom during the heating of the flask.

The ring 13 is preferably demountably supported within the casing. As indicated in 2, the ringis provided with a de pending tubular portlon 10 adapted telescopically to be received in the upper open end of a gas passage formed by a tube 23 integrally cast on the inner face of the casting andlongitudinally extending thereof. The lower end of this tube is open and a valve gas outlet is inserted therein to dispermits the spacing of the charge combustible gas into the tube 23 and thence to the ring passage and finally to the tubular members. This tube 23 preferably has an aperture 20 adjacent the gas outlet in order to permit the admixture of a quan tity of air to the gas discharged so that a hot flame, analogous to that of a Bunsen burner may be delivered at the ported tubular members 14:.

The gas outlet here disclosed is of a common commercial form having a tip which is received in threaded engagement within the head, 25 having a gas passage therethrough which is adapted to be opened or closed by means of the valve 27 on the shaft 28. The valve shaft 28 has an arm 29 formed with a terminal eye. 2 V

In this novel construction, this eye receives therethrough the end of a tension springBl by which means the arm 29is constantly upwardly pulled to effect closure oi the valve- The arm 32 extends in the opposite direction from the arm 29 and is terminally apertured to receive a pin 33 projecting from the end of the link 34 pivotally carried by the Ill-shaped crank 35 pinned to the shaft borne at its inner end in a novel bearing formed on the base oil the head The shaft 30 outwardly extends through the casing where it is terminally provided with a lmurled head 36 whereby the shaft may be manually rotated toopen the gas outlet. Obviously-the spring 31 may be disconnected and the opening and closure of the gas valve controlled by the knurled head,

The gas head 25 is formed with a projecting flange which is interiorly threaded to receive a pipe 37 supported by, and extending within, the casing which pipe is adapted to be connected to a suitable source of supply oi combustible gas. I

The head .25 of this old form oi valve structure is also provided with a by-pass around the valve 27 to which is connected the relatively slender tube 39 so that the byass and tube are uncontrolled by the valve. In this novel combination, the tube 39 is suitably connected to the pilot tube 42 which upwardly extends and terminates adjacent one of the tubular members 14-. During the employment of this device, the pilot gas is kept burning so as to effect the instant-ignition -of gas discharge from the tubular members 14: upon opening of the valve 27. Thelflo'w of through the pilot tube is controlled, in this particular common form of gas tip and head, by'mea us of the screw 7 By the employment of this novel device, the molecules free water in the investment material adjacent the flash are, under influ ence of the suddenheating to a high temperature, partially converted into steam and driven inwardly from the flask sides. This steam drives ahead of it the adjacent partially boiling free Water to of the flask sides the pattern chamber sothat -the successive outer'portions of the invested wax are pro gressively melted and carr ed out oi' the investment material by way-of the sprueholc which offers the line of least resistance. Continuance of penetration of the steam and hot free water completely flushes out the pattern chamber of all traces wax. The heat is preferably shut off before the steam ceases to issue from the sprue hole in order that the water of crystallization of the investment material surrounding the wax pattern cham her is not driven off with the resultant mold cracks and warpage of the investment material. This melting of the wax and flushing of the mold prevents the usual formation of the lining of carbon residue in the mold interior. This carbonized lining is disadvantageous inthat the mold is thereby inaccurately made smaller than the original tooth cavity in direct proportion to the thick ness of the lining.

We claim as our invention:

1. A heating device having a casing, means in said casing to support an object to be heated, hollow means in said casing disposed about said object and adapted to discharge gas tangentially to said object, and means to supply a combustible gas to said hollow means.

2. A heating device having a casing providing means to support an object to be heated, said supporting means forming a passage for gas, tubular members projecting from and communicating with the supporting means, the members being apertured to discharge gas substantially tangentially toward a supported object, and means to supply a combustible gas to said passage.

3. A heating device having a casing providing means to support an object to be heated, said supporting means forming a passage for gas, tubular members projecting from and communicating with supporting means, said members being annularly disposed and apertured to discharge gas tangentially toward a supported object, and means to supply a combustible gas to said passage.

4. A heating device having a casing providing an upright tubular element adapted to be connected adjacent its lower end with a supply of combustible gas and forming a passage therefor, means to support an ob ject to be heated, a plurality of tubular members connected to said'element and adapted to discharge gas adjacent a supported'object, and means adjacent the lower end of said element to permit air to be mixed with the supplied gas.

5. A heating device having a casing providing an upright tubular element adapted to be connected adjacent its lower end with a supply of combustible gas, a hollow instrumentality mounted upon the upper end of said element and adapted to receive gas be guided to the cup.

therefrom, saidinstrumentality being adapted to support an obj ect to be heated, tubular members communicating. withjsaid instrumentality and-aperturedto discharge gas adjacent a supported object.

- A heating device havlng a. casing'providing anfupright tu'bula'r element, means to support anobjectto be heated, a plurality of tubularmembers-connected to said'element and adapted to dischargegasadjacent a supported object, a pilot tube adapted to discharge gas adjacent said members, means to supply combustible gas tothe element and pilottube, and a valve to control the gas supplied to said element.

7. A heating device having a casing, pro- 7 viding a hollow ring-like instrumentality carried by the casing, a plurality of upright tubular members projecting from and communicating with said instrumentality and adapted inwardly to jet combustiblegas,

means to supply a combustible gas to said instrumentality whereby the gas will be jetted from said members, means to support an object to be heated within the space annularly defined by the tubular members whereby upon ignition of the jetted gas the object will be heated and material may drop through the ring-like instrumentality. I

8. A heating device having a casing providing a drip cup, means to support the drip cup in the casing, means to support an invested dental flask on said cup in spacedreannular passage and ported inwardly to jet gas, a drip cup supported by and extending below said annular passage, means on-said cup to support an invested dental flask whereby the flask may extend upwardly between said ported members and be heated by the ignited ported gas, whereby the melted wax and moisture may collect in the cup.

10. A heating device having a casing providing an elongated upright element, adapted to be connected adjacent its lower end. with a supply of combustible gas and form-' ing a passage therefor, a hollow ring-like instrumentality carried by the easing, a depending tubular projection on said instrumentality adapted to be connected to the upper end of said element and to receive gas therefrom, a plurality of upright tubular members annularly projecting from and communicating with said .instrumentality and apertured to discharge gas substantially inwardly, and means to support an object Within said annularly disposed tubular men bfilS, whereby upon ignition of the discharged gas, the object Will be heated.

11. A heating device having a casing pro- 0 viding an elongated upright tubular element adapted to be connected adjacent its lower end with a supply of combustible gas and forming a passage therefor, means in said casing to support an object to be heated, a -10 plurality of tubular members projecting from and communicating with said element, the members being apeitui'ed to discharge gas substantially tangentially toward a supported object, and means to supply a combustible gas to said element.

In Witness whereof, We have herennto set our hands this 18th day of March, 1921'.

KARL W. KNAPP. WALTER e. HOLMES. 

